Pycnometric and Spectroscopic Studies of Red Phosphors Ca2+(1-1.5x)WO4:Eu3+xand Ca2+(1-2x)WO4:Eu3+x,Na+x

Cho, Seon-Woog

doi:10.5012/bkcs.2013.34.9.2769

Cited by 8 publications

(5 citation statements)

References 19 publications

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“…For example, A 2+ in ABO 4 (A = Ca or Sr, B = W or Mo) can be successfully substituted by co-doping of Eu 3+ /M + (M = Li, Na, or K), which in fact, could greatly enhance the luminescence intensity. 15,[25][26][27] Besides, one has proved that the scheelite structure allows the existence of A-site vacancies, i.e. M 2/7 Gd 4/7 □ 1/7 MoO 4 (M = Li + or Na + ; □ = A-site vacancies), therefore, the occurrence of cation vacancies along with Eu 3+ doping is another way of charge balance.…”

Section: Introductionmentioning

confidence: 99%

Structural investigation of the A-site vacancy in scheelites and the luminescence behavior of two continuous solid solutions A_1–1.5xEu_x□_0.5xWO₄ and A_0.64–0.5yEu_0.24Li_y□_0.12–0.5yWO₄ (A = Ca, Sr; □ = vacancy)

et al. 2015

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Scheelite compounds with Eu(3+) substitution are well-known red-phosphors. We prepared and performed a detailed structural characterization of A(1-1.5x)Eu(x)□(0.5x)WO4 and A(0.64-0.5y)Eu(0.24)Li(y)□(0.12-0.5y)WO4 (A = Ca, Sr; □ = vacancy) to confirm the A-site vacancy mechanism for charge balance when bivalent A cations were substituted by Eu(3+). All compounds crystallize in I4₁/a with a disordered arrangement of A(2+), Eu(3+), □ at the A-site. The title compounds are all good red phosphors with a high R/O ratio (∼10), indicating that Eu(3+) is located at a significantly distorted cavity. A(1-1.5x)Eu(x)□(0.5x)WO4 shows a saturation phenomenon at a high doping level, x = 0.20. With the incorporation of Li(+), the emission intensity was generally enhanced compared to the Li(+)-free samples, moreover, an increase of the Li(+) content reduces the content of vacancies, resulting in further increase of the luminescence intensity.

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Section: Introductionmentioning

confidence: 99%

Structural investigation of the A-site vacancy in scheelites and the luminescence behavior of two continuous solid solutions A_1–1.5xEu_x□_0.5xWO₄ and A_0.64–0.5yEu_0.24Li_y□_0.12–0.5yWO₄ (A = Ca, Sr; □ = vacancy)

et al. 2015

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“…Two experimental peaks occur at approximately 822 and 862 cm –1 . 26 , 34 Accurate IR absorption experiments in this region will be necessary in the future. Applying a high-power terahertz laser to a CaWO 4 crystal will endow the phonons of the W–O vibrational mode with high energy-absorption efficiency, which may facilitate chemical bond breakage and W separation from CaWO 4 .…”

Section: Resultsmentioning

confidence: 99%

Theoretical Study of Efficient Photon–Phonon Resonance Absorption in the Tungsten-Related Vibrational Mode of Scheelite

Yin,

Li,

Liu

et al. 2024

ACS Omega

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Tungsten (W) is an extremely rare and vital metal extensively used in metallurgy, the chemical industry, optoelectronic devices, and machinery manufacturing. In this work, an environmentally friendly and efficient physical method based on photon−phonon resonance absorption (PPRA) is proposed for separating W from scheelite. We calculated the vibrational spectrum of calcium tungstate (CaWO 4 ) and assigned the infrared (IR) absorption and Raman scattering peaks through a dynamic analysis of the normal modes. We focused on the strong IR absorption peaks related to W and identified three high-intensity IR-active modes at around 830 cm −1 , corresponding to the stretching of the W− O bonds. Therefore, we propose the use of high-power terahertz (∼25 THz) laser radiation to facilitate W extraction from compounds, leveraging the high efficiency of PPRA. Experimental testing is required to determine the precise absorption frequency under industrial production conditions.

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“…(1) and (2) in Kröger-Vink notation, 5) respectively. Mechanism (1) produces one vacancy V Ca " for every substitution of two Tb 3+ ions into three Ca 2+ sites.…”

Section: +mentioning

confidence: 99%

“…In a series of previous papers, 1,2) we presented the physical properties of red phosphors Ca (1-1.5x) WO 4 : and Ca (1-2x) WO 4 :…”

Section: Introductionmentioning

confidence: 99%

Point Defects and Photoluminescence of Green Phosphors Ca(1-1.5x)WO4:Tbx3+ and Ca(1-2x)WO4:Tbx3+ Nax+

Cho¹

2013

Korean. J. Mater. Res.

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Two types of Tb-and Na-substituted green phosphors Ca (1-1.5x) WO 4 :and Ca (1-2x) WO 4 : were synthesized with various x values, using a solid-state reaction. The former phosphors contained both substitutional and vacancy point defects, while the later had only substitutional defects. X-ray diffraction results showed that the main diffraction peak, (112), was centered at 2θ = 28.72 o and indicated that there was no basic structural deformation caused by substitutions or vacancies. The photoluminescence emission and photoluminescence excitation spectra revealed the optical properties of trivalent terbium ions, Tb 3+. Typical transitions,F 3 , and cross relaxations were observed. Subtle differences in the photoluminescence of green phosphors were observed as a result of the point defects. The FT-IR spectra indicated that some of the ungerade vibrational modes had shifted positions and changed shapes, spreading out over a wide range of frequencies. This change can be attributed to the different masses of Tb 3+ and Na + ions and V Ca " vacancies compared to Ca 2+ ions. The gerade normal modes of the Raman spectra exhibited subtle differences resulting from point defects in Ca (1-1.5x) Tb x WO 4 and Ca (1-2x) Tb x Na x WO 4 .

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Pycnometric and Spectroscopic Studies of Red Phosphors Ca²⁺_(1-1.5x)WO₄:Eu³⁺_xand Ca²⁺_(1-2x)WO₄:Eu³⁺_x,Na⁺_x

Cited by 8 publications

References 19 publications

Structural investigation of the A-site vacancy in scheelites and the luminescence behavior of two continuous solid solutions A_1–1.5xEu_x□_0.5xWO₄ and A_0.64–0.5yEu_0.24Li_y□_0.12–0.5yWO₄ (A = Ca, Sr; □ = vacancy)

Structural investigation of the A-site vacancy in scheelites and the luminescence behavior of two continuous solid solutions A_1–1.5xEu_x□_0.5xWO₄ and A_0.64–0.5yEu_0.24Li_y□_0.12–0.5yWO₄ (A = Ca, Sr; □ = vacancy)

Theoretical Study of Efficient Photon–Phonon Resonance Absorption in the Tungsten-Related Vibrational Mode of Scheelite

Point Defects and Photoluminescence of Green Phosphors Ca(1-1.5x)WO4:Tbx3+ and Ca(1-2x)WO4:Tbx3+ Nax+

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Pycnometric and Spectroscopic Studies of Red Phosphors Ca2+(1-1.5x)WO4:Eu3+xand Ca2+(1-2x)WO4:Eu3+x,Na+x

Cited by 8 publications

References 19 publications

Structural investigation of the A-site vacancy in scheelites and the luminescence behavior of two continuous solid solutions A1–1.5xEux□0.5xWO4 and A0.64–0.5yEu0.24Liy□0.12–0.5yWO4 (A = Ca, Sr; □ = vacancy)

Structural investigation of the A-site vacancy in scheelites and the luminescence behavior of two continuous solid solutions A1–1.5xEux□0.5xWO4 and A0.64–0.5yEu0.24Liy□0.12–0.5yWO4 (A = Ca, Sr; □ = vacancy)

Theoretical Study of Efficient Photon–Phonon Resonance Absorption in the Tungsten-Related Vibrational Mode of Scheelite

Point Defects and Photoluminescence of Green Phosphors Ca(1-1.5x)WO4:Tbx3+ and Ca(1-2x)WO4:Tbx3+ Nax+

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Pycnometric and Spectroscopic Studies of Red Phosphors Ca²⁺_(1-1.5x)WO₄:Eu³⁺_xand Ca²⁺_(1-2x)WO₄:Eu³⁺_x,Na⁺_x

Structural investigation of the A-site vacancy in scheelites and the luminescence behavior of two continuous solid solutions A_1–1.5xEu_x□_0.5xWO₄ and A_0.64–0.5yEu_0.24Li_y□_0.12–0.5yWO₄ (A = Ca, Sr; □ = vacancy)

Structural investigation of the A-site vacancy in scheelites and the luminescence behavior of two continuous solid solutions A_1–1.5xEu_x□_0.5xWO₄ and A_0.64–0.5yEu_0.24Li_y□_0.12–0.5yWO₄ (A = Ca, Sr; □ = vacancy)